Superordinate categorization via learned stimulus equivalence: Quantity of reinforcement, hedonic value, and the nature of the mediator.

Three experiments examined superordinate categorization via stimulus equivalence training in pigeons. Experiment 1 established superordinate categories by association with a common number of food pellet reinforcers, plus it established generalization to novel photographic stimuli. Experiment 2 documented generalization of choice responding from stimuli signaling different numbers of food pellets to stimuli signaling different delays to food reinforcement. Experiment 3 indicated that different numbers of food pellets did not substitute as discriminative stimuli for the photographic stimuli with which the food pellets had been paired. The collective results suggest that the effective mediator of superordinate categories that are established via learned stimulus equivalence is not likely to be an accurate representation of the reinforcer, neither is it likely to be a distinctive response that is made to the discriminative stimulus. Motivational or emotional mediation is a more likely account. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evidence that type III iodothyronine deiodinase in rat astrocyte is a selenoprotein

A type III iodothyronine deiodinase (D-III) that inactivates thyroid hormones has been recently cloned and identified as a selenoprotein in neonatal rat skin. However, selenium (Se) deficiency does not affect the D-III activity in the rat placenta and decreases the D-III in the rat brain only slightly. This study examines the effect of Se on the D-III activity in cultures of rat brain astrocytes. Astrocytes were depleted in Se by maintaining them in Se-free chemically defined medium for 7 days. These conditions decreased the activity of a recognized selenoprotein, glutathione peroxidase, 3-10-fold. D-III activity induced by 12-0-tetradecanoylphorbol-13-acetate (TPA) was also decreased 2-6-fold. Addition of 30 nM Se to the culture medium caused a rapid increase in TPA-induced D-III activity visible within 1 h. This Se effect was maximal at 3 h (4-fold increase) and dose-dependent. Se also increased the induction of D-III by acidic Fibroblast Growth Factor, 8-bromo-cAMP, T4, or retinoic acid. Cycloheximide blocked the effect of Se on TPA-induced D-III activity, whereas actinomycin D did not. Thus the rapid effect of Se does not require messenger RNA synthesis but requires protein synthesis. We conclude that the D-III in astrocytes is probably a selenoprotein.     

Enhancing workplace competence acquisition through a persuasive system

The continuous development of individual competences is a fundamental instrument for organizations aiming to achieve long-term competitive advantage. Digital technologies can play a pivotal role in competence acquisition by facilitating the learning process. This paper describes the design, development, and evaluation process of a competence acquisition mobile app incorporating persuasive systems principles. A pilot study involving managers from an IT consulting firm was used to evaluate the artifact. This was followed by a full-scale deployment of the mobile app with management and staff of a supermarket chain. The results indicate that the use of the mobile app effectively improved users’ learning process outcomes, as well as their ability to deploy the new competence. Theoretical and practical contributions are discussed.

     

Assessment of a non-adaptive deterministic global optimization algorithm for problems with low-dimensional non-convex subspaces

The optimum and at least one optimizing point for convex nonlinear programs can be approximated well by the solution to a linear program (a fact long used in branch and bound algorithms). In more general problems, we can identify subspaces of ‘non-convex variables’ such that, if these variables have sufficiently small ranges, the optimum and at least one optimizing point can be approximated well by the solution of a single linear program. If these subspaces are low-dimensional, this suggests subdividing the variables in the subspace a priori, then producing and solving a fixed, known number of linear programs to obtain an approximation to the solution. The total amount of computation is much more predictable than that required to complete a branch and bound algorithm, and the scheme is ‘embarrassingly parallel’, with little need for either communication or load balancing. We compare such a non-adaptive scheme experimentally to our GlobSol branch and bound implementation, on those problems from the COCONUT project Lib1 test set with non-convex subspaces of dimension four or less, and we discuss potential alterations to both the non-adaptive scheme and our branch and bound process that might change the scope of applicability.     

空中伊甸园

这是Jean Nouvel第一次在新加坡设计项目,这个住宅项目地处新加坡市中心Orchard(乌节)路的南端,是一个距离闹市很近却又闹中取静的地段。嘉蜂豪庭,从字面上看可以感受到"豪华的、庭院……"这样的概念,事实上也的确很豪华。33层高的建筑物一共只容纳43家住户,在寸土寸金的地段打造了空中别墅的居住梦想。目前建筑还未建成,我们所能了解到的仅是建筑的模型和效果图,以及开发和设计团队的理念。     

Structural Behavior of Short Span Precast Channel Beam Bridges without Shear Reinforcement

This paper presents findings of a research study conducted by the writers for the Arkansas State Highway and Transportation Department. The study investigated precast nonprestressed concrete channel beam sections cast without shear reinforcement used in short, multispan bridges. The original objective of the study was to establish a correlation for inspection purposes between the beam’s visual deteriorated state and its corresponding approximate structural capacity. However, during four-point load testing of 33 beams, it was found that beam strength was more a function of a beam’s concrete compression strength rather than deterioration state. A national survey of state transportation departments within the contiguous states was conducted by the authors and found that 13 states currently use precast channel beam bridges. The particular section considered in this paper is a 5.79?m (19?ft) precast channel beam section used to cross small streams and depressions; however constructed without shear reinforcing steel. Bridges using these sections were constructed in the 1950s through to the early 1970s and were designed for H15 loading. Thirty-three formally in-service beams, in various states of deterioration, were load tested. The writers found that the majority of the beams exhibited load capacity greater than the initially required H15 design strength. Second, member strength was a function of concrete compressive strength. Of the 33 beams load tested, 28 beams showed ductile behavior; conversely, the other five beams failed without exhibiting a yield plateau.     

Drug permeation behavior through thermo- and pH-responsive polycarbonate-g-poly(N-isopropylacrylamide-co-acrylic acid) composites

Poly(N-isopropylacrylamide-co-acrylic acid) hydrogel was grafted onto track-etched polycarbonate (PC) films using the free-radical polymerization method to prepare thermo-sensitive micro-porous films. Differential scanning calorimeter analysis was used to determine the lower critical solution temperature for the hydrogels. Thermo-gravimetric analysis was used to determine the thermal stability of the PC–hydrogel composite films. The composite films were characterized using Fourier transform-infrared spectra, scanning electron microscope, and effective pore diameters derived from water permeability data. 4-Acetamidophenol, citric acid, KCl, and methyl orange were used as the model drugs. For neutral drugs, the larger molecules exhibited lower permeability but higher on–off ratio than smaller ones. The strong electrolyte model molecules (KCl) exhibited depressed permeability due to enlarged hydrated ion sizes. The acidic (citric acid) model solution promoted gel shrinkage, resulting in increased drug permeability and on–off ratio.     

Situation awareness-based agent transparency and human-autonomy teaming effectiveness

ABSTRACT

Effective collaboration between humans and agents depends on humans maintaining an appropriate understanding of and calibrated trust in the judgment of their agent counterparts. The Situation Awareness-based Agent Transparency (SAT) model was proposed to support human awareness in human–agent teams. As agents transition from tools to artificial teammates, an expansion of the model is necessary to support teamwork paradigms, which require bidirectional transparency. We propose that an updated model can better inform human–agent interaction in paradigms involving more advanced agent teammates. This paper describes the model's use in three programmes of research, which exemplify the utility of the model in different contexts – an autonomous squad member, a mediator between a human and multiple subordinate robots, and a plan recommendation agent. Through this review, we show that the SAT model continues to be an effective tool for facilitating shared understanding and proper calibration of trust in human–agent teams.     

Evaluation of retail fresh meat packagings covered with stretch films of plasticized PVC and non‐PVC alternatives

The characteristics and performance of several non‐PVC stretch films were compared to those of plasticized PVC. Initially the main polymer components of the film were identified by infrared spectrometry and differential scanning calorimetry. The differences between films in mechanical properties, such as puncture resistance and tensile strength, varied about a factor of two, while the differences in elongation at break were considerably higher. Plasticized PVC showed properties somewhere in the middle. The water vapour transmission was highest for PVC, while its permeability to oxygen was the lowest. The potential for overall migration was assessed by substitute testing, using 95% ethanol and isooctane as test media, and the migration from PVC was found to be the highest. However, after use of the appropriate reduction factor of four, as allowed for fresh meat, the PVC film also proved to conform to legislation. The potential for specific migration was investigated by solvent extraction followed by gas chromatography. Twenty‐four components were identified, of which 11 could be compared to relevant migration limits based on evaluations of the EU Scientific Committee for Food. The release of solvents was estimated by direct thermal desorption at 100°C. Four films of different composition were used in a storage experiment with fresh beef. The meat quality was followed by measurements of colour, microbiological quality (total colony forming units and lactic acid bacteria) and lipid oxidation (thiobarbituric acid reactive substances) through a prolonged shelf‐life test. No differences in meat quality during normal shelf‐life were seen as a function of the film used. Copyright © 2004 John Wiley & Sons, Ltd.